The present invention relates to an air bag assemblies and more particularly to a driver side air bag and assembly.
Various types of driver side air bag assemblies have been proposed for protecting an occupant against injury. Typically, the driver side air bag assembly comprises a housing, a gas generator, typically using a solid propellant such as sodium azide, and an air bag. The air bag is maintained in a folded configuration and secured in this configuration to the housing by a cover.
Typical of prior art air bags are those illustrated in U.S. Pat. Nos. 4,966,389 and 5,033,771 which show the use of three and four narrow strips of material used as tethers. One disadvantage of using three or four tethers arises from the fact that an air bag will occasionally deploy or inflate asymmetrically, that is, one portion of the air bag may inflate faster than another. This asymmetric deployment may occur because of the way the air bag is folded or perhaps because of the design of the gas inflator (gas generator). When an air bag inflates an initial shock load is created. In a tethered air bag, this shock load occurs when any of the tethers reaches its fully extended condition. When an air bag inflates asymmetrically the shock load may be absorbed by less than all of the tethers. In this situation the tether or tethers being subjected to this shock load could be damaged. Another disadvantage of prior art air bags which use a large number of tethers is that the additional material used for the tethers prevents the air bag from being folded compactly. This arises because each tether must be folded any number of times prior to achieving the final, folded configuration of the air bag.
It is an object of the present invention to provide an air bag assembly including an air bag which improves upon the deficiencies in the prior art.
Accordingly, the invention comprises: an air bag comprising: an upper panel and a lower panel both of woven material sewn together forming a generally circular structure; tether means of the same material as one of the upper and lower panels for controlling the shape of the air bag as same is inflated by inflation gas and for absorbing a shock load created upon inflation. The tether means comprising a central portion secured to the upper panel and only two tethers extending oppositely therefrom. The central portion and tethers being of integral construction, and being of sufficient strength such that each tether can separately withstand the shock load without being damaged, and reinforcement means secured to the lower panel and to respective ends of the each tether remote from the center portion for securing the ends of each tether relative to the lower panel. The invention also includes an assembly utilizing the air bag, a retaining ring and gas generator.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.